The present invention relates to a method and an apparatus for conveying items.
Said items being preferably, but not exclusively, in the form of rolls with substantially cylindrical shape obtained by transversely cutting a single body or elongated stick and having a respective longitudinal axis, which are advanced along a longitudinal path of advance, preferably, with its own axis oriented according to the direction of advance.
Preferably, but not exclusively, such items are in the form of rolls of paper, plastic, metallic, or similar material destined mainly to household use, for instance rolls of toilet paper, absorbing paper, plastic film or aluminium foil or others for wrapping food products and other items.
The present conveying apparatus is positioned between a working machine situated upstream, such as a machine for cutting and separating into items from said stick or elongated body, and one or more machines for working said items, such as machines for packing said items into respective packaging containers.
In the industry, there are machines for cutting and separating and for packing rolls, both operating at great speed.
Currently, to transport said items from said upstream machine to said downstream packaging machines, the items or rolls exiting the upstream working machine are accelerated and mutually distanced, mainly in order to create, between an item and the other, a space suitable for the performance of operations to distribute the items onto the different secondary lines of the apparatus.
To provide for said operations for distributing the items, the conveyed items are therefore subjected to stops, which serve to re-aggregate the previously detached items, followed by abrupt accelerations, which cause the items to reach high speeds, and which are effected mainly in order to attempt to recover at least part of the time wasted during said stops.
Such a traditional manner of operating on the items, however, presents numerous drawbacks.
A first drawback concerns the damage, consumption and wear whereto the items are subjected, and consequently also the conveyor belts that transport them and the related guides. Such consumption and wear are caused by the high rubbing stresses between the items and the means for transporting them, stresses whose main cause is the high levels of acceleration and speed reached in said known systems.
Such damage to the rolls is aggravated even further by the locking action provided by mechanical assemblies for stopping the rolls used in known conveying lines.
Another drawback concerns the upsets whereto a certain number of such conveyed items are subjected, especially those presenting modest length, again due to such excessive accelerations and speeds. In order to overcome such drawbacks, the presence of a certain number of personnel assigned to intervene to remove the upset items from the line becomes necessary. Such removal actions, however, cannot always be timely, so in spite of them the items cause clogging along the line, resulting in consequent stops of the line itself, with the deriving efficiency losses and slow average speeds of advance of the products.
In particular, in such known conveying apparatus, it is also common for the items produced by said cutting machines to be picked up by conveyor belts that generally travel at higher speed than that of the transferring means of said cutting machine and come to be mutually distanced from the initial phases of the conveying operation.
It has been observed that such a distancing of the items is a cause for the upset of the items themselves along the conveying line.
A further negative aspect also stems from an excessive use of motive force necessary to subject the products to such high levels of speed and acceleration, whereby it is attempted to overcome the normally provided stops of the items themselves or the stops caused by the upsetting of items along said line.
According to the present invention, a method is provided for conveying items according to claim 1. In particular, a method is provided for conveying items by means of a conveying apparatus comprising a line for conveying said items from a machine for working said items situated upstream, which advances and transfers to the line said items at a predetermined speed, to a utilisation situated downstream; characterised in that, at least in the initial part of said conveying line downstream of the working machine, the speed of advance of said items is maintained substantially equal to the speed of advance and transfer of said working machine situated upstream.
In this way it is possible to maintain, at least in the initial part of the conveying apparatus, a conveying speed that is not excessively high, allowing to obtain sufficiently low consumption and wear to the items and the belt. Said speed being at the same time sufficiently high to attain a considerable average conveying speed.
The present invention enables to avoid successively accelerating and stopping the items, as was instead the case with prior art apparatuses.
Moreover, especially if short items are to be conveyed, the risk of upsetting them along the line is minimised, avoiding to the utmost extent the need for interventions on the part of the personnel.
In short, a considerable productionxe2x80x94meant as quantities delivered per unit of timexe2x80x94is obtained, greater than the one obtained with prior art apparatuses.
Moreover, a considerable structural and functional simplification of the present apparatus with respect to known apparatuses is obtained, eliminating, among other things, the presence of dedicated stopping and accelerating units.
A lower consumption of motive power with respect to known devices is also achieved.
According to a further aspect, a method is provided for conveying items, said items being advanced along a longitudinal path of advance starting from a machine for working said items situated upstream at least to a machine for treating said items situated downstream, characterised in that, to carry longitudinally said items from said upstream machine to said downstream machine, said items are advanced in longitudinal groups or trains of items; and in that, in each group or train of items, said items are longitudinally approached to each other.
Since said items are to be conveyed by being maintained longitudinally grouped together, in such away that the distance between adjacent items is such that if an item rotates or is upset, it comes in contact with an item of said group that is adjacent thereto, it is possible to prevent said upsets of the items from occurring. Hence one avoids, on one hand, the need for intervention on the personnel""s part and, on the other hand, any stops to the line that feeds the items. In short, a very high production is obtained, exceeding that of known conveying systems.
Additional advantageous aspects are shown in the other claims.
The present invention further relates to an apparatus for conveying items that realises the method for conveying items according to the present invention.
Further features of the present invention shall become more readily apparent from the detailed description that follows, made with reference to the accompanying drawings, which represent embodiments provided purely by way of non limiting example.